Ford Ka - Heater getting not getting hot

[3sixty]

The OH has a Ford Ka and when we got it, it all worked fine. Fast forward a year and the fan stopped working altogether. As a fix, I replaced the resistor in the passenger footwell and all works fine.

However, over the last few days the heater is not getting hot. Occasionally on long journeys it will turn "less cold" but not face melting hot I would expect on full power.

We have replaced the resistor as above and also the heater valve, but neither has made any difference to the heat.

Anyone any ideas?

[jiimbo]

The potentiometer behind the heater control knob is probably broken (short-circuit).

Given your symptoms (no heat) that is the only possible cause, since the heater valve default setting (i.e. when getting no power) is fully open = full heat all the time.

You are getting no heat = control valve gets full power all the time = short circuit in potentiometer.

Hopefully this makes sense!

[3sixty]

Makes a little sense!

Searched google and comes up with throttle potentiometer, this isnt the same I presume?

Is it a DIY fix?

[jiimbo]

Not sure about the throttle potentiometer...

But the heater potentiometer is an easy DIY fix. Just take the panel off.

I don't know what Ford charges for a new one. Knowing Ford ka spare part prices, it could be anything from a few pounds to a hefty sum...

[holderd]

Another potential cause is the heater control valve. Its quite a common fault on Ka's (I do believe).

My mum's went about 1 1/2 years into ownership. You can get the valve on ebay for about £20 and its about an hours work with a good guide. If I remember right its underneath the scuttle panel....

[HereBeMonsters]

Not a simple airlock in the coolant? Have you fiddled with the system recently?

[3sixty]

Thanks for the replies guys.

Any idea where I can get the heater potentiometer from except the dealers? Did a few quick searches and google didnt throw much up.


I have already replaced the heater control valve, thats what I meant to say in the OP when talking about the valve. Could possibly be an airlock, how can I work it free?

[HereBeMonsters]

3sixty said:

Thanks for the replies guys.

Any idea where I can get the heater potentiometer from except the dealers? Did a few quick searches and google didnt throw much up.


I have already replaced the heater control valve, thats what I meant to say in the OP when talking about the valve. Could possibly be an airlock, how can I work it free?

Run it with the rad cap off, pump the hoses with your hand. Not sure where airlocks can occur on the Ka's layout, unfortunately.

To be fair, you'd probably notice the car overheating a tad if there was an airlock. More likely to be the electrical gubbins mentioned above.

[3sixty]

HereBeMonsters said:

3sixty said:

Thanks for the replies guys.

Any idea where I can get the heater potentiometer from except the dealers? Did a few quick searches and google didnt throw much up.


I have already replaced the heater control valve, thats what I meant to say in the OP when talking about the valve. Could possibly be an airlock, how can I work it free?

Run it with the rad cap off, pump the hoses with your hand. Not sure where airlocks can occur on the Ka's layout, unfortunately.

To be fair, you'd probably notice the car overheating a tad if there was an airlock. More likely to be the electrical gubbins mentioned above.

Thanks for that. Just been out to change a headlight bulb (Which needed the hands of a 4 year old, but I managed... just) and let it run for a while and did as above, will see if that solves it.

In the meantime if anyone has a guide to replacing the potentiometer and possibly a part number, as I'm struggling to find it online.

[3sixty]

Bump for this.

Trying to speak to Ford parts and they have never heard of a potentiometer (Or at least the 2 I spoke to haven't)

They keep wanting to sell me a heater valve, which I have already replaced. Anyone any ideas of any other names for the potentiometer, or a part number?

Cheers

[3sixty]

Last bump for this... desperately need a part number as Ford Dealer hasn't a clue what a potentiometer is

[Zad]

If the blower is not blowing, then the resistor pack has failed (again).

If there is no heat coming through the cabin heater, then the heater control valve has died. Common fault. Google Ka heater not working or Ka heater control valve.

[3sixty]

Zad said:

If the blower is not blowing, then the resistor pack has failed (again).

If there is no heat coming through the cabin heater, then the heater control valve has died. Common fault. Google Ka heater not working or Ka heater control valve.

Thanks - but as said in the OP, I have replaced the resistor and the heater control valve. Any other suggestions?

[Zad]

What I'm getting at is that I have replaced stuff in the past, only for the replacement to be faulty. If you have a multimeter, measure the voltage on the valve and on the fan to make sure it is activating. If the voltage isn't there then you need a circuit diagram from a Haynes manual or whatever, and trace the voltage back. An air lock is still a possibility if the heater matrix is the highest point in the water circuit.